The Stardust spacecraft has successfully negotiated the Earth fly-by which scientists planned for it.
The probe passed close by the planet, using the Earth's gravity to sling it towards a comet.
Scientists hope the mission will collect dust flying from the comet and bring it back to earth in a capsule.
Nasa's craft passed over the southern tip of Africa at a height of 3,700 miles.
Stardust is now expected to rendezvous with Comet Wild 2 in January 2004.